Sky segmentor using canny lines

ABSTRACT

A method includes receiving a first image. The method also includes detecting a plurality of edges in the first image. The method also includes connecting the edges. The method also includes identifying a contour in the first image based at least partially upon the connected edges. The method also includes determining a convex hull of the contour. The method also includes generating a second image comprising the convex hull.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 63/048,799, filed on Jul. 7, 2020, the entirety of which isincorporated by reference herein.

FIELD OF THE DISCLOSURE

The present disclosure is directed to sky segmentation. Moreparticularly, the present disclosure is directed to performing skysegmentation on an image or video frame to help a vehicle determine thedivide (e.g., horizon) between the ground and the sky for navigationpurposes and/or to detect an object in the vehicle's field of view.

BACKGROUND

Sky segmentation uses a machine-learning model to associate pixels in animage or video frame with the sky. Sky segmentation methods aretypically either edge-based or content-based. Edge-based skysegmentation methods do not produce a complete pixel-by-pixel skysegmentation. Rather, they conclude with finding a horizon line formicro air vehicle attitude estimation. Content-based sky segmentationmethods require large amounts of pixel-by-pixel hand-labeled data, andthey also have a high computational cost. In addition to the foregoingshortcomings, neither method works well with limited labeled data andreal-time runtime constraints.

SUMMARY

A method is disclosed. The method includes receiving a first image. Themethod also includes detecting a plurality of edges in the first image.The method also includes connecting the edges. The method also includesidentifying a contour in the first image based at least partially uponthe connected edges. The method also includes determining a convex hullof the contour. The method also includes generating a second imagecomprising the convex hull.

A computing system is also disclosed. The computing system includes oneor more processors and a memory system. The memory system includes oneor more non-transitory computer-readable media storing instructionsthat, when executed by at least one of the one or more processors, causethe computing system to perform operations. The operations includereceiving a first image. The first image is captured by a camera on anaircraft in flight. The operations also include detecting a plurality ofedges in the first image based at least partially upon a threshold. Theoperations also include connecting the edges. The operations alsoinclude identifying a largest contour in the first image based at leastpartially upon the connected edges. The operations also includedetermining a convex hull of the largest contour. The convex hullrepresents a portion of a ground region in the first image. Theoperations also include generating a second image comprising the convexhull. A plurality of first pixels in the second image represent theconvex hull, and a plurality of second pixels in the second image do notrepresent the convex hull.

In another example, the operations include receiving a first image. Thefirst image is captured by a camera on a vehicle. The operations alsoinclude detecting a plurality of edges in the first image based at leastpartially upon a threshold. The operations also include connecting theedges. The edges are connected using morphological closing with a squarekernel, and the morphological closing uses a kernel having an area fromabout 20 pixels to about 50 pixels. The operations also includeidentifying a largest contour in the first image based at leastpartially upon the connected edges. The largest contour includes alargest area. The operations also include determining a convex hull ofthe largest contour. The convex hull represents a portion of a groundregion in the first image. The operations also include generating asecond image including the convex hull. A plurality of first pixelshaving a first color in the second image represent the convex hull, anda plurality of second pixels having a second color in the second imagedo not represent the convex hull. The operations also includeidentifying a bottom-most first pixel in each column in the secondimage. The operations also include converting the second pixels that arebelow the bottom-most first pixel in each column to first pixels toproduce a modified second image. The first pixels in the modified secondimage represent the ground region, and the second pixels in the modifiedsecond image represent a sky region. The operations also includecombining at least a portion of the first image and at least a portionof the modified second image to produce a combined image.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate aspects of the present teachingsand together with the description, serve to explain the principles ofthe present teachings.

FIG. 1 illustrates a schematic view of an aircraft in flight, accordingto an example.

FIG. 2 illustrates a flowchart of a method for segmenting an image intoa sky region and a ground region, according to an example.

FIG. 3 illustrates a first image captured by a camera on the aircraft inflight, according to an example.

FIG. 4 illustrates the first image with a plurality of edges identified,according to an example.

FIG. 5 illustrates the first image with the edges connected, accordingto an example.

FIG. 6 illustrates the first image with a largest contour identified,according to an example.

FIG. 7 illustrates the first image with a convex hull identified,according to an example.

FIG. 8 illustrates a second image including a plurality of first pixels(e.g., black pixels) representing the convex hull, according to anexample.

FIG. 9 illustrates the second image with a bottom-most first pixel(e.g., the bottom-most black pixel) identified in each column, accordingto an example.

FIG. 10 illustrates the second image with second pixels (e.g., whitepixels) below the bottom-most first pixel (the bottom-most black pixel)converted to first pixels (e.g., black pixels) to produce a modifiedsecond image, according to an example.

FIG. 11 illustrates a combined image that includes the modified secondimage overlaid onto the first image, according to an example.

It should be noted that some details of the figures have been simplifiedand are drawn to facilitate understanding rather than to maintain strictstructural accuracy, detail, and scale.

DESCRIPTION

Reference will now be made in detail to the present teachings, examplesof which are illustrated in the accompanying drawings. In the drawings,like reference numerals have been used throughout to designate identicalelements. In the following description, reference is made to theaccompanying drawings that form a part thereof, and in which is shown byway of illustration specific examples of practicing the presentteachings. The following description is, therefore, merely exemplary.

The systems and methods disclosed herein may identify/produce a boundarythat approximates the separation between a ground region and a skyregion in an image. The systems and methods may also mask out thenon-sky (e.g., ground) region from the image to produce a skybackground, which may minimize false positives of the boundary and/ordetected objects. The system and methods disclosed herein may require notraining data and run at or near real-time to generate a pixel-by-pixelsky segmentation map. Once the boundary has been detected, the systemand method may use the boundary to help detect objects (e.g., otheraircrafts, birds, etc.) and to navigate the aircraft to avoid suchobjects. The accuracy of the detection process may be enhanced byemploying the sky segmentation technique described herein.

The systems and methods may quickly and accurately detect non-skyregions within an image which have a nonlinear border. In addition, thesystems and methods do not require labeled data to train amachine-learning (ML) model. The systems and methods segment non-skyregions pixel-by-pixel, rather than by finding a horizon line anddividing the image into “above horizon” and “below horizon.”

The camera may be fixed to the aircraft at a defined position relativeto the aircraft with its field of view directed toward a region ofinterest (e.g., forward and/or in the direction that the aircraft istravelling). The sky regions may be entirely contained above non-skyregions. The non-sky regions may contain more edge sections than skyregions do. The sky and non-sky regions are separated by a horizon: amoderately straight line which traverses most to all of the width of theimage. An example of the system and method may divide the image into skyand non-sky regions.

FIG. 1 illustrates a schematic view of an aircraft 100 in flight,according to an example. The aircraft 100 may be or include an airplane,a helicopter, an unmanned aerial vehicle (e.g., a drone), a spacecraft,or the like. The aircraft 100 may include a camera 110. The camera 110may be coupled the aircraft 100 and/or positioned within the aircraft100. The camera 110 may be configured to capture one or more images. Thecamera 110 may also or instead be configured to capture a video. In oneexample, the camera 110 may be configured to capture a continual streamof images over time (i.e. a video), and the images may be still framestaken from the video.

The images and/or video may be transmitted to a computing system 120 onthe aircraft 100. In another example, the computing system 120 may belocated on the ground (e.g., in a control station) in communication withan on-board computing system that is on/in the aircraft 100. Thecomputing system 120 may include one or more processors and a memorysystem. The memory system may include one or more non-transitorycomputer-readable media storing instructions that, when executed by atleast one of the one or more processors, cause the computing system 120to perform operations. The operations are described with reference toFIG. 2 below.

FIG. 2 illustrates a flowchart of a method 200 for segmenting an imageinto a sky region and a ground region, according to an example. Anillustrative order of the method 200 is described below. One or moresteps of the method 200 may be performed in a different order, repeated,or omitted.

The method 200 may include receiving a first image, as at 202. Anexample of the first image 300 is shown in FIG. 3. The first image 300may be received by the computing system 120. As mentioned above, thefirst image 300 may be captured by the camera 110. The camera 110 may bein an upright position and pointed forward such that the first image 300includes a region of interest in the direction that the aircraft 100 ismoving. Thus, the first image 300 may include at least a portion of theflight path of the aircraft 100. The first image 300 may include aground region 310, a sky region 320, or both.

The method 200 may also include detecting a plurality of edges (threeare identified: 410, 420, 430) in the first image 300, as at 204. FIG. 4shows the edges 410, 420, 430 detected/identified in the first image300. As used herein, an “edge” refers to a point, set of points, or line(e.g., one or more pixels) in an image where the brightness changessharply (e.g., by more than a predetermined threshold). Although thefirst image 300 includes more than three edges, for the sake ofsimplicity, only three are identified. This step may be performed by thecomputing system 120. More particularly, the computing system 120 mayuse canny edge detection (e.g., with low hysteresis parameters) orLaplacian edge detection methods to detect the edges 410, 420, 430 inthe first image 300. In at least one example, the detection may be basedat least partially upon a sensitivity threshold. For example, thesensitivity threshold may be increased (e.g., by a user) to detect moreedges in the first image 300, or the sensitivity threshold may bedecreased to detect fewer edges in the first image 300. In at least oneexample, the first image 300 may be binary, and pixels representing anedge 410, 420, 430 may have a value of zero, and pixels that do notrepresent an edge 410, 420, 430 may have a value of one, or vice versa.

The method 200 may also include connecting one or more of the edges 410,420, 430 in the first image 300, as at 206. FIG. 5 shows the edges 410,420, 430 (from FIG. 4) after being connected to produce connected edges510, 520, 530. This step may be performed by the computing system 120.More particularly, the computing system 120 may use morphologicalclosing to produce the connected edges 510, 520, 530. The morphologicalclosing may use a kernel with an area from about 2 pixels to about 200pixels, about 5 pixels to about 150 pixels, about 10 pixels to about 100pixels, or about 20 pixels to about 50 pixels. The kernel may have ashape that is substantially a square, a rectangle, a triangle, a circle,an oval, an ellipse, or the like.

The method 200 may also include identifying one or more contours (threeare shown: 610, 620, 630) in the first image 300, as at 208. FIG. 6shows the contours 610, 620, 630 in the first image 300. This step maybe performed by the computing system 120. The contours 610, 620, 630 maybe identified based at least partially upon the connected edges. Forexample, the contours 610, 620, 630 may each have an uninterruptedperimeter that is defined by the connected edges. In an example, thefirst image 300 may include a plurality of contours 610, 620, 630, andthis step may include identifying the largest contour 610, which isoutlined with a hatching pattern to be seen more clearly. The largestcontour 610 may be or include the contour with the most pixels (e.g.,the largest area).

The method 200 may also include determining a convex hull 710 of the(e.g., largest) contour 610, as at 210. FIG. 7 shows the convex hull 710of the contour 610. This step may be performed by the computing system120. The convex hull 710 is outlined with a hatching pattern todemonstrate and describe the step 210. In practice, such hatching may ormay not be used. As used herein, a “convex hull” refers to the smallestconvex shape that (e.g., entirely) surrounds another shape (e.g., thecontour 610). Thus, no line can be drawn from a first point inside ofthe shape to a second point inside of the shape that at some point alongthe line falls outside of the shape. The convex hull 710 represents aportion of the ground region 310 in the first image 300. The top 720 ofthe convex hull 710 may represent the horizon (e.g., between the groundregion 310 and the sky region 320).

The method 200 may also include generating a second image 800, whichincludes the convex hull 710, as at 212. Alternatively, the first image300 may be modified to produce the second image 900, which includes theconvex hull 710. FIG. 8 shows the second image 800, which includes theconvex hull 710. This step may be performed by the computing system 120.The second image 800 may include a plurality of first (e.g., black)pixels 810 and a plurality of second (e.g., white) pixels 820. The firstpixels 810 may represent the convex hull 710, which represents at leasta part of the ground region 310. The second pixels 820 do not representthe convex hull 710. Instead, at least a portion of the second pixels820 may represent the sky region 320. For example, the second pixels 820that are above the first pixels 810 may represent the sky region 320.However, as may be seen, some of the second pixels 820 are below thefirst pixels 810. As the sky region 320 cannot be below the groundregion 310, this is corrected below.

The method 200 may also include identifying a bottom-most first pixel911 in a column 910 in the second image 800, as at 214. This is shown inFIG. 9. This step may be performed by the computing system 120. Thisstep may be repeated for each column in the second image 800. This mayyield a bottom-most layer 920 of first pixels 810 in the second image800. The bottom-most layer 920 is outlined with a hatching pattern to beseen more clearly.

The method 200 may also include converting the second pixels 820 thatare below the bottom-most first pixel 911 in the column 910 to firstpixels 810 to produce a modified second image 1000, as at 216. This isshown in FIG. 10. This step may be performed by the computing system120. This corrects the issue noted above. Now, the first pixels 810represent the ground region 310, and the second pixels 820 represent thesky region 320. There is no longer a portion of the sky region 320 thatis positioned below the ground region 310. The modified second image1000 may be or include a sky mask. As used herein, a “sky mask” refersto a binary image where “false” (e.g., 0) values indicate ground pixelsand “true” (e.g., 1) values indicate sky pixels.

In an example, the method 200 may also include combining the first image300 and at least a portion of the modified second image 1000 to producea combined image 1100, as at 218. This is shown in FIG. 11. This stepmay be performed by the computing system 120. In at least one example,this may include overlaying at least a portion of the modified secondimage 1000 on the first image 300 to produce the combined image 1100.The portion of the modified second image 1000 that is overlaidsubstantially corresponds to the ground region 310 in the first image300. As shown, the portion of the modified second image 1000 may betransparent or opaque such that the first image 300 underneath may beseen. In FIG. 11, the portion of the modified second image 1000 ishatched to be seen more clearly. In another example, the portion of themodified second image 1000 may be solid such that the first image 300underneath may not be seen. In yet another example, this step may beomitted.

The method 200 may also include navigating (e.g., steering) the aircraft100, as at 220. The aircraft 100 may be navigated (e.g., steered) basedat least partially upon the second image 800, the modified second image1000, the combined image 1100, or a combination thereof. The navigationmay be performed (e.g., automatically) by the computing system 120. Inanother example, the navigation may be performed by a user. The user maybe in the aircraft 100 (e.g., a pilot), or the user may be on the groundand steering the aircraft 100 remotely.

In another example, the method 200 may also or instead include detectingone or more objects, as at 222. This step may be performed by thecomputing system 120. The objects may be detected based at leastpartially upon the second image 800, the modified second image 1000, thecombined image 1100, or a combination thereof. For example, the secondimage 800, the modified second image 1000, and/or the combined image1100 may be used as an input into a path-planning or object detectionalgorithm. The object detection algorithm may more accurately detectobjects and/or detect objects with fewer false positives when the imageis segmented into the sky and non-sky regions, which enables detectionof the objects above the horizon (e.g., in the sky region). The objectsdetected may be or include moving objects. For example, the objects maybe or include other aircrafts in flight, and the aircraft 100 may benavigated in response to (e.g., to avoid) the other aircrafts in flight.

As used herein, the terms “inner” and “outer”; “up” and “down”; “upper”and “lower”; “upward” and “downward”; “upstream” and “downstream”;“above” and “below”; “inward” and “outward”; and other like terms asused herein refer to relative positions to one another and are notintended to denote a particular direction or spatial orientation. Theterms “couple,” “coupled,” “connect,” “connection,” “connected,” “inconnection with,” and “connecting” refer to “in direct connection with”or “in connection with via one or more intermediate elements ormembers.” Similarly, the terms “bonded” and “bonding” refer to “directlybonded to” or “bonded to via one or more intermediate elements, members,or layers.”

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the disclosure are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Moreover, all ranges disclosed hereinare to be understood to encompass any and all sub-ranges subsumedtherein.

While the present teachings have been illustrated with respect to one ormore examples, alterations and/or modifications can be made to theillustrated examples without departing from the spirit and scope of theappended claims. In addition, while a particular feature of the presentteachings may have been disclosed with respect to only one of severalexamples, such feature may be combined with one or more other featuresof the other examples as may be desired and advantageous for any givenor particular function. As used herein, the terms “a”, “an”, and “the”may refer to one or more elements or parts of elements. As used herein,the terms “first” and “second” may refer to two different elements orparts of elements. As used herein, the term “at least one of A and B”with respect to a listing of items such as, for example, A and B, meansA alone, B alone, or A and B. Those skilled in the art will recognizethat these and other variations are possible. Furthermore, to the extentthat the terms “including,” “includes,” “having,” “has,” “with,” orvariants thereof are used in either the detailed description and theclaims, such terms are intended to be inclusive in a manner similar tothe term “comprising.” Further, in the discussion and claims herein, theterm “about” indicates that the value listed may be somewhat altered, aslong as the alteration does not result in nonconformance of the processor structure to the intended purpose described herein. Finally,“exemplary” indicates the description is used as an example, rather thanimplying that it is an ideal.

It will be appreciated that variants of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be combined intomany other different systems or applications. Various presentlyunforeseen or unanticipated alternatives, modifications, variations, orimprovements therein may be subsequently made by those skilled in theart which are also intended to be encompasses by the following claims.

Clause 1: A method comprising receiving a first image; detecting aplurality of edges in the first image; connecting the edges; identifyinga contour in the first image based at least partially upon the connectededges; determining a convex hull of the contour; and generating a secondimage comprising the convex hull.

Clause 2: The method of Clause 1, wherein the first image is captured bya camera on an aircraft in flight.

Clause 3: The method of Clause 1 or 2, wherein the edges are connectedusing morphological closing, and wherein the morphological closing usesa kernel having an area from about 2 pixels to about 200 pixels.

Clause 4: The method of any of Clauses 1-3, wherein the convex hullrepresents a portion of a ground region in the first image.

Clause 5: The method of Clause 4, wherein a plurality of first pixels inthe second image represent the convex hull.

Clause 6: The method of Clause 5, wherein a plurality of second pixelsin the second image do not represent the convex hull.

Clause 7: The method of Clause 6, wherein a portion of the second pixelsrepresent a sky region in the first image.

Clause 8: The method of Clause 6 or 7, further comprising identifying abottom-most first pixel in a column in the second image; and convertingthe second pixels that are below the bottom-most first pixel in thecolumn to first pixels to produce a modified second image.

Clause 9: The method of Clause 8, further comprising steering theaircraft based at least partially upon the modified second image.

Clause 10: The method of Clause 8 or 9, further comprising detecting asecond aircraft in flight based at least partially upon the modifiedsecond image.

Clause 11: A computing system comprising one or more processors; and amemory system comprising one or more non-transitory computer-readablemedia storing instructions that, when executed by at least one of theone or more processors, cause the computing system to performoperations, the operations comprising receiving a first image, whereinthe first image is captured by a camera on an aircraft in flight;detecting a plurality of edges in the first image based at leastpartially upon a threshold; connecting the edges; identifying a largestcontour in the first image based at least partially upon the connectededges; determining a convex hull of the largest contour, wherein theconvex hull represents a portion of a ground region in the first image;and generating a second image comprising the convex hull, wherein aplurality of first pixels in the second image represent the convex hull,and wherein a plurality of second pixels in the second image do notrepresent the convex hull.

Clause 12: The computing system of Clause 11, wherein the edges areconnected using morphological closing, and wherein the morphologicalclosing uses a kernel having an area from about 10 pixels to about 100pixels.

Clause 13: The computing system of Clause 11 or 12, wherein theoperations further comprise identifying a bottom-most first pixel ineach column in the second image; and converting the second pixels thatare below the bottom-most first pixel in each column to first pixels toproduce a modified second image, wherein the first pixels in themodified second image represent the ground region, and wherein thesecond pixels in the modified second image represent a sky region.

Clause 14: The computing system of Clause 13, wherein the operationsfurther comprise combining at least a portion of the first image and atleast a portion of the modified second image to produce a combinedimage.

Clause 15: The computing system of Clause 14, wherein the operationsfurther comprise transmitting or displaying a notification to steer theaircraft based at least partially upon the combined image.

Clause 16: A computing system comprising one or more processors; and amemory system comprising one or more non-transitory computer-readablemedia storing instructions that, when executed by at least one of theone or more processors, cause the computing system to performoperations, the operations comprising receiving a first image, whereinthe first image is captured by a camera on an aircraft in flight;detecting a plurality of edges in the first image based at leastpartially upon a threshold; connecting the edges, wherein the edges areconnected using morphological closing with a square kernel, and whereinthe morphological closing uses a kernel having an area from about 20pixels to about 50 pixels; identifying a largest contour in the firstimage based at least partially upon the connected edges, wherein thelargest contour comprises a largest area; determining a convex hull ofthe largest contour, wherein the convex hull represents a portion of aground region in the first image; generating a second image comprisingthe convex hull, wherein a plurality of first pixels having a firstcolor in the second image represent the convex hull, and wherein aplurality of second pixels having a second color in the second image donot represent the convex hull; identifying a bottom-most first pixel ineach column in the second image; converting the second pixels that arebelow the bottom-most first pixel in each column to first pixels toproduce a modified second image, wherein the first pixels in themodified second image represent the ground region, and wherein thesecond pixels in the modified second image represent a sky region; andcombining at least a portion of the first image and at least a portionof the modified second image to produce a combined image.

Clause 17: The computing system of Clause 16, wherein combining at leasta portion of the first image and at least a portion of the modifiedsecond image comprises overlaying a portion of the modified second imagethat corresponds to the ground region on the first image.

Clause 18: The computing system of Clause 17, wherein the modifiedsecond image is at least partially transparent when overlaid on thefirst image.

Clause 19: The computing system of any of Clauses 16-18, furthercomprising detecting a second aircraft in flight based at leastpartially upon the combined image.

Clause 20: The computing system of Clause 19, further comprisingtransmitting or displaying a notification to steer the aircraft based atleast partially upon a trajectory of the second aircraft.

What is claimed is:
 1. A method, comprising receiving a first image;detecting a plurality of edges in the first image; connecting the edges;identifying a contour in the first image based at least partially uponthe connected edges; determining a convex hull of the contour; andgenerating a second image comprising the convex hull.
 2. The method ofclaim 1, wherein generating the second image comprises modifying thefirst image to generate the second image.
 3. The method of claim 1,wherein the first image is captured by a camera on an aircraft inflight.
 4. The method of claim 1, wherein the convex hull represents aportion of a ground region in the first image.
 5. The method of claim 4,wherein a plurality of first pixels in the second image represent theconvex hull.
 6. The method of claim 5, wherein a plurality of secondpixels in the second image do not represent the convex hull.
 7. Themethod of claim 6, wherein a portion of the second pixels represent asky region in the first image.
 8. The method of claim 6, furthercomprising: identifying a bottom-most first pixel in a column in thesecond image; and converting the second pixels that are below thebottom-most first pixel in the column to first pixels to produce amodified second image.
 9. The method of claim 8, further comprisingnavigating the aircraft based at least partially upon the modifiedsecond image.
 10. The method of claim 8, further comprising detecting anobject in space based at least partially upon the modified second image.11. A computing system comprising: one or more processors; and a memorysystem comprising one or more non-transitory computer-readable mediastoring instructions that, when executed by at least one of the one ormore processors, cause the computing system to perform operations, theoperations comprising: receiving a first image, wherein the first imageis captured by a camera on an aircraft in flight; detecting a pluralityof edges in the first image based at least partially upon a threshold;connecting the edges; identifying a largest contour in the first imagebased at least partially upon the connected edges; determining a convexhull of the largest contour, wherein the convex hull represents aportion of a ground region in the first image; and generating a secondimage comprising the convex hull, wherein a plurality of first pixels inthe second image represent the convex hull, and wherein a plurality ofsecond pixels in the second image do not represent the convex hull. 12.The computing system of claim 11, wherein the edges are connected usingmorphological closing, and wherein the morphological closing uses akernel having an area from about 10 pixels to about 100 pixels.
 13. Thecomputing system of claim 11, wherein the operations further comprise:identifying a bottom-most first pixel in each column in the secondimage; and converting the second pixels that are below the bottom-mostfirst pixel in each column to first pixels to produce a modified secondimage, wherein the first pixels in the modified second image representthe ground region, and wherein the second pixels in the modified secondimage represent a sky region.
 14. The computing system of claim 13,wherein the operations further comprise combining at least a portion ofthe first image and at least a portion of the modified second image toproduce a combined image.
 15. The computing system of claim 14, whereinthe operations further comprise causing the aircraft to navigate basedat least partially upon the combined image.
 16. A computing systemcomprising: one or more processors; and a memory system comprising oneor more non-transitory computer-readable media storing instructionsthat, when executed by at least one of the one or more processors, causethe computing system to perform operations, the operations comprising:receiving a first image, wherein the first image is captured by a cameraon a vehicle; detecting a plurality of edges in the first image based atleast partially upon a threshold; connecting the edges, wherein theedges are connected using morphological closing with a square kernel,and wherein the morphological closing uses a kernel having an area fromabout 20 pixels to about 50 pixels; identifying a largest contour in thefirst image based at least partially upon the connected edges, whereinthe largest contour comprises a largest area; determining a convex hullof the largest contour, wherein the convex hull represents a portion ofa ground region in the first image; generating a second image comprisingthe convex hull, wherein a plurality of first pixels having a firstcolor in the second image represent the convex hull, and wherein aplurality of second pixels having a second color in the second image donot represent the convex hull; identifying a bottom-most first pixel ineach column in the second image; converting the second pixels that arebelow the bottom-most first pixel in each column to first pixels toproduce a modified second image, wherein the first pixels in themodified second image represent the ground region, and wherein thesecond pixels in the modified second image represent a sky region; andcombining at least a portion of the first image and at least a portionof the modified second image to produce a combined image.
 17. Thecomputing system of claim 16, wherein combining at least a portion ofthe first image and at least a portion of the modified second imagecomprises overlaying a portion of the modified second image thatcorresponds to the ground region on the first image.
 18. The computingsystem of claim 17, wherein the modified second image is at leastpartially transparent when overlaid on the first image.
 19. Thecomputing system of claim 16, further comprising detecting an objectbased at least partially upon the combined image.
 20. The computingsystem of claim 19, further comprising causing the vehicle to navigatebased at least partially upon a trajectory of the object.